Unique characteristics of the pyrrolysine system in the 7th order of methanogens: implications for the evolution of a genetic code expansion cassette.

摘要: Pyrrolysine (Pyl), the 22nd proteogenic amino acid, was restricted until recently to few organisms. Its translational use necessitates presence of enzymes for synthesizing it from lysine, a dedicated amber stop codon suppressor tRNA, and specific amino-acyl tRNA synthetase. The three genomes proposed Thermoplasmata-related 7th order methanogens contain complete genetic set Pyl synthesis its use. Here, we have analyzed genomic features Pyl-coding system in these with those previously known Bacteria Archaea phylogeny each component. This shows unique peculiarities, notably an imperfect anticodon stem shortened Phylogenetic analysis indicates that present ancestor seventh appears more closely related than Methanosarcinaceae, suggesting involvement lateral gene transfer spreading pyrrolysine between two prokaryotic domains. We propose likely emerged once Archaea, hydrogenotrophic methanol-H 2-dependent methylotrophic methanogen. close relationship methanogenesis provides possible example expansion still evolving code, shaped by metabolic requirements.